shaun

Whats up guys.
Im finally putting my engine back together and i was putting the cams in whennn a cam cap bolt snapped off in the block.
After cursing and crying i got it out of the head with a reversed thread drill bit
Went down to mazda and 2 days later i have an oem bolt. Sweet!
Now lets just get this done and over with right?

NO! another old bolt breaks off in the head and i rage quit and walk away

I need to go back and get another bolt but i was wondering guys...

Is there some tricks to make old bolts a bit stronger maybe?
My thought is i could maybe warm them a bit before attempting to get this damn cam bolted in and hopefully they'll just stretch a bit before breaking?

thirdgen

iTrader: (26)

What are you torquing them at? Make sure your torque wrench is for inch / lbs and not ft/ lbs. If your manual says something like 30 inch /lbs and you set your torque wrench for 30 ft/lbs (cause you though it was an inch lbs wrench) then obviously you'll be wayyyy over tightening your bolts, thus causing them to break.
If that's not the case, buy all brand new bolts.

rleete

iTrader: (21)

You should run a tap through the threads in the block before rebuilding, to clean up any buggered threads. Make sure to flush out the chips completely. Discard any rusty bolts, or ones with messed up threads.

But I agree, you are probably way over-torqueing those bolts.

shaun

The first time I was using an inch lbs wrench and I think it was 45 but the second time around I was just getting them tight by hand with a wrench and it wasn't very tight, just enough till they stopped moving. Was just giving them all a last check and added a little more to one and it popped.

Im not asking what im doing wrong im just asking if i can strengthen them without buying all new bolts cause that'll get expensive lol

jt@namiata.com

Been there. Prior owner over torqued most of the hardware required to do the last tb/wp job. Nothing went back in to torque spec - it either stretched or broke.

Replace the hardware.

concealer404

iTrader: (3)

And make sure you're not bringing the cam in where it's supposed to be WITH the bolts.

curly

iTrader: (25)

I'm not quite sure how you're supposed to compress the cam without using the bolts. I always have...

Sounds like another person over torqued the bolts. Check all of them for necking and replace.

concealer404

iTrader: (3)

I'm not saying don't compress it with the bolts...

I'm saying don't bring the cam down in the journals with the bolts. Like... an inch out or whatever.

I cringe every time i see that.

Efini~FC3S

iTrader: (4)

Make sure the bolts are dry as are the threads you are torquing them into as well. Any sort of lubricant/oil will significantly affect the friction coefficient of the bolted joint, transferring more tensile load into the bolt for the same amount of torque applied to it.

That is, you can pop m6 bolts if you are torquing them when they are oily. The oil lessons the friction in the threads and transfers all of the torque as bolt load and over stresses the fastener. This condition is worsened if the bolt has already been over-torqued (ie already plastically deformed).

So, were they oily/wet at all?

TheScaryOne

iTrader: (3)

Odds are a PO or a grease monkey with gorilla arms overtorqued them all.

Hmm. Could one install studs and used flanged nuts to avoid stressing the threads in the delicate aluminum head? Boltdepot has 14.9 grade M6 "set screws" in lengths from 8 to 50 mm and 10.9 flanged hex nuts to match.

turbofan

iTrader: (1)

"I keep breaking bolts. Can you make them stronger"

"Let's first make sure the simple things are fixed..."

"NO. I WANT TO MAKE THE BOLTS STRONGER."

Ok derp.

Jeffbucc

Something my dad taught me when wrenching on bicycles. When torquing those small bolts/screws/allens, grip the socket wrench by the head, not the tail. That way you have a lot harder time physically being able to over-tighten something

Also tap&die everything if you feel the slightest resistance. I've worn out a couple M6x1.0 taps.

Start threading the bolt by hand, your skin gives you better feedback than a wrench.